1. Nutrient Cycles and Climate Change

2. Material Cycles Hydrologic Cycle - path of water through the environment – Solar energy continually evaporates water stored in the oceans and land, and distributes water vapor around the globe. Condenses over land surfaces, supporting all terrestrial systems – Responsible for cellular metabolism, nutrient flow in ecosystems, and global distribution of heat and energy

3. Hydrologic Cycle

4. Carbon Cycle Begins with intake of CO 2 during photosynthesis. Carbon atoms are incorporated into sugar which is eventually released by cellular respiration either in the plant or in organisms that consumed it. Sometimes the carbon is not recycled for a long time. Coal and oil are the remains of organisms that lived millions of years ago. The carbon in these is released when we burn them. Some carbon is also locked in calcium carbonate (shells, limestone).

5. Carbon Cycle The parts of the cycle that remove carbon dioxide from the atmosphere (vegetation) are called carbon sinks. The parts of the cycle that release carbon dioxide are called carbon sources. Burning of fuels generates huge quantities of carbon dioxide that cannot be taken up fast enough by the carbon sinks. This excess carbon dioxide contributes to global warming.

6. Carbon Cycle

7. Nitrogen Cycle Nitrogen is needed to make proteins and nucleic acids such as DNA (Chap. 2). Plants take up inorganic nitrogen from the environment and build protein molecules which are later eaten by consumers. – Nitrogen-fixing bacteria change nitrogen to a more useful form by combining it with hydrogen to make ammonia. Other bacteria convert ammonia to nitrites and nitrates, which can be taken up by plants to make proteins. Members of the bean family (legumes) have nitrogen-fixing bacteria living in their root tissue.

8. Nitrogen Cycle – Nitrogen re-enters the environment: Death of organisms Excrement and urinary wastes – Nitrogen re-enters atmosphere when denitrifying bacteria break down nitrates into N 2 and nitrous oxide (N 2 O) gases. Humans have profoundly altered the nitrogen cycle via use of synthetic fertilizers, nitrogen-fixing crops, and fossil fuels.

9. Nitrogen Cycle

10. Phosphorous Cycle Phosphorous is needed to make DNA, ATP (the energy currency of the cell) and other important biomolecules (Chap. 2). Phosphorous compounds are leached from rocks and minerals and usually transported in aqueous form. – Taken in and incorporated by producers Passed on to consumers – Returned to environment by decomposition Cycle takes a long time as deep ocean sediments are significant sinks

11. Phosphorus Cycle

12. Sulfur Cycle Most sulfur is tied up in underground rocks and minerals. Inorganic sulfur is released into air by weathering and volcanic eruptions. – Cycle is complicated by large number of oxidation states the element can assume. – Human activities release large amounts of sulfur, primarily by burning fossil fuels. Important determinant in rainfall acidity

13. Sulfur Cycle

14. Weather, Climate and the Atmosphere

15. Global Warming is Happening Most important environmental issue of our time In 2007, the Intergovernmental Panel on Climate Change released its fourth report. – Represents a consensus by more than 90% of all scientists working on climate – Gives a probability value of 90% that the warming we are now seeing is caused by humans

16. Global Warming Range of temperature increase predicted to be from 1.1 to 6.4°C (2 to 11.5°F) by 2100 depending on population growth, energy conservation, etc. Best estimate is 1.8 to 4°C (3.2 to 7.8°F) – To put that in perspective, there has been a 5 degree C rise since the middle of the last ice age (about 20,000 years ago).

17. Global Warming Most people will experience more extreme weather including droughts, floods, heat waves and hurricanes. These extremes have increased significantly in the last decade. In the worst outcome, we could see millions of human deaths. Sea levels are projected to rise 17-57 cm (7 to 23 in). If we do nothing, Greenland’s ice will melt and raise sea levels 20 ft.

18. Global Warming If Greenland’s ice melts, a great deal of land will be flooded including: – Most of Florida – Some of the Gulf Coast – Most of Manhattan – Shanghai – Hong Kong – Tokyo

19. Sources of Greenhouse Gases Carbon Dioxide - fossil-fuel burning Atmospheric levels increasing steadily Most important cause of warming Methane - ruminants, rice paddies Absorbs more infrared than CO 2. Chlorofluorocarbons (CFC’s) - refrigerants Declined in developed countries, but now produced in developing nations. Nitrous Oxide - burning organic material

20. Sources of Greenhouse Gases U.S. has less than 5% of world’s population but produces 28% of carbon dioxide. China, with 1.3 billion people, is second. Japan and Europe produce half as much carbon dioxide per person as the U.S.

21. Controlling Greenhouse Emissions Reducing carbon dioxide levels – Renewable energy sources Double average fuel economy Switch to efficient lighting and appliances Wind turbines Biofuels – Capture and store carbon dioxide Planting vegetation Injection into wells

22. Progress Made United Kingdom has rolled back its CO 2 emissions to 1990 levels and is aiming for a 60% reduction by 2050. Germany has reduced CO 2 by 10%. Denmark gets 20% of its electricity from windmills, and plans to increase that to 50%. China reduced its emissions 20% between 1997 and 2005. (At its present rate, U.S. will be 25% above 1990 emissions in 5 years. No progress.)

23. Carbon Management Capturing and storing carbon dioxide Build “trees” in which calcium hydroxide solution would absorb carbon dioxide Plant forests Fertilize the oceans with iron to permit phytoplankton growth, which would take up carbon dioxide Inject carbon dioxide underground or in ocean

24. Synthetic “Trees” that Capture Carbon Dioxide